linux-kernel - Re: [PATCH v9 8/8] iio: adc: ad4851: add ad485x driver

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Message-ID: <d4ur7trhknm7jtjvsyms4aewypl75uuvgtccgwc7dfycheh4qo@jqmpv5t3lip6>
Date: Fri, 17 Jan 2025 10:59:04 +0100
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>
Cc: jic23@...nel.org, robh@...nel.org, conor+dt@...nel.org, 
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pwm@...r.kernel.org
Subject: Re: [PATCH v9 8/8] iio: adc: ad4851: add ad485x driver

Hello,

On Fri, Dec 20, 2024 at 02:01:34PM +0200, Antoniu Miclaus wrote:
> +static const int ad4851_oversampling_ratios[] = {
> +	1, 2, 4, 8, 16,	32, 64, 128,
> +	256, 512, 1024, 2048, 4096, 8192, 16384, 32768,
> +	65536,
> +};
> +
> +static int ad4851_osr_to_regval(unsigned int ratio)
> +{
> +	int i;
> +
> +	for (i = 1; i < ARRAY_SIZE(ad4851_oversampling_ratios); i++)
> +		if (ratio == ad4851_oversampling_ratios[i])
> +			return i - 1;
> +
> +	return -EINVAL;
> +}

This can be simplified (I guess) using something like:

	if (ratio >= 2 && ratio <= 65536 && is_power_of_2(ratio))
		return ilog2(ratio) - 1;

	return -EINVAL;

> +static void __ad4851_get_scale(struct iio_dev *indio_dev, int scale_tbl,
> +			       unsigned int *val, unsigned int *val2)
> +{
> [...]
> +}
> +
> +static int ad4851_scale_fill(struct iio_dev *indio_dev)
> +{
> [...]
> +}
> +
> +static int ad4851_set_oversampling_ratio(struct iio_dev *indio_dev,
> +					 const struct iio_chan_spec *chan,
> +					 unsigned int osr)
> +{
> [...]
> +}
> +
> +static int ad4851_get_oversampling_ratio(struct ad4851_state *st, unsigned int *val)
> +{
> +	unsigned int osr;
> +	int ret;
> +
> +	guard(mutex)(&st->lock);
> +
> +	ret = regmap_read(st->regmap, AD4851_REG_OVERSAMPLE, &osr);
> +	if (ret)
> +		return ret;
> +
> +	if (!FIELD_GET(AD4851_OS_EN_MSK, osr))
> +		*val = 1;
> +	else
> +		*val = ad4851_oversampling_ratios[FIELD_GET(AD4851_OS_RATIO_MSK, osr) + 1];

With the suggestion above this gets:

	*val = 2 << FIELD_GET(AD4851_OS_RATIO_MSK, osr);

(or 
	*val = 1 << (FIELD_GET(AD4851_OS_RATIO_MSK, osr) + 1);

). Then you can drop ad4851_oversampling_ratios[].

> +
> +	st->osr = *val;
> +
> +	return IIO_VAL_INT;
> +}

Best regards
Uwe

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